---
id: "CVE-2026-99053"
kind: "vulnerability"
aliases: ["CVE-2026-99053"]
title: "Linux kernel TIPC: use-after-free when netlink handlers reach freed nodes"
severity: "unknown"
cvss: null
epss: 0.00209
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["linux-kernel", "runtime", "self-hosted", "tipc"]
not_affected_if: ["tipc-module-not-loaded"]
published_at: "2026-10-23T13:17:28+00:00"
first_seen_at: "2026-10-23T21:57:33+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99053", "first_seen_at": "2026-10-23T21:57:33+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-99053", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Linux kernel TIPC: use-after-free when netlink handlers reach freed nodes

The TIPC networking code in the Linux kernel looked up a node by link name and used it after leaving the RCU read lock without holding a reference, so a timer-driven cleanup could free the node mid-use. A local or netlink-capable user could trigger a use-after-free in kernel memory, which may allow privilege escalation, though the sources do not state an exploit outcome.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the running kernel version with `uname -r` and compare it against the fixed kernel release in the NVD entry.
- Check whether TIPC is loaded with `lsmod | grep tipc`; unknown whether the sources give a further check.

## Fix

- Update the Linux kernel to a release that includes the upstream fix referenced in the NVD entry (fixed version: unknown from the sources).

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99053
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-99053

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

tipc: hold a reference to nodes found by link name

tipc_node_find_by_name() returns a node after dropping its RCU read lock
without taking a reference.  The LINK_SET, LINK_GET and LINK_RESET_STATS
handlers then lock and access the node, racing with timer-driven cleanup of
a down peer.  Generic netlink serialization does not exclude the node
timer.

The following interleaving can leave a handler using a freed node:

  CPU 0: find the node under RCU and release the node read lock
  CPU 1: tipc_node_timeout() clears the links and unlinks the down node
  CPU 1: drop the list and timer references, queuing tipc_node_free()
  CPU 0: leave the RCU read-side critical section
  CPU 1: complete the grace period and free the node
  CPU 0: acquire the node lock through the stale pointer

LINK_SET also uses the node's media address after releasing the node lock,
when passing queued packets to tipc_bearer_xmit().

KASAN on v7.3-rc5 reported:

  BUG: KASAN: slab-use-after-free in _raw_read_lock_bh
  Write of size 4 at addr ffff88807e06f008 by task poc/92
  Call Trace:
   _raw_read_lock_bh                 kernel/locking/spinlock.c:287
   tipc_nl_node_set_link             net/tipc/node.c:2475
   genl_family_rcv_msg_doit          net/netlink/genetlink.c:1114
   genl_rcv_msg                      net/netlink/genetlink.c:1209
   netlink_rcv_skb                   net/netlink/af_netlink.c:2575

  Allocated by task 0:
   tipc_node_create                  net/tipc/node.c:539
   tipc_node_check_dest              net/tipc/node.c:1196
   tipc_disc_rcv                     net/tipc/discover.c:252

  Freed by task 92:
   kfree                             mm/slub.c:6801
   rcu_core                          kernel/rcu/tree.c:2919

  Last potentially related work creation:
   __call_rcu_common.constprop.0     kernel/rcu/tree.c:3181
   tipc_node_timeout                 net/tipc/node.c:814

Acquire a reference to the selected node with kref_get_unless_zero() before
leaving RCU, returning NULL if the node has already been released.  Release
that reference on every caller exit after the last node access, including
transmission in LINK_SET.  Keep the existing link lookup order and locking
so concurrent link removal still takes the existing error paths.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_